The present invention relates generally to rotary heat exchangers and, more specifically, to an integrated means for removing and replacing basketed material within duct work or an air preheater rotor.
A rotary regenerative heat exchanger is employed to transfer heat from one hot gas stream, such as a flue gas stream, to another cold gas stream, such as combustion air. The rotor contains a mass of heat absorbent material which is first positioned in a passageway for the hot gas stream where heat is absorbed by the heat absorbent material. As the rotor turns, the heated absorbent material enters the passageway for the cold gas stream where the heat is transferred from the absorbent material to the cold gas stream.
In a typical rotary heat exchanger, such as a rotary regenerative air preheater, the cylindrical rotor is disposed on a central rotor post and divided into a plurality of sector-shaped compartments by a plurality of radial partitions, known as diaphragms, extending from the rotor post to the outer peripheral shell of the rotor. These sector shaped compartments are loaded with modular heat exchange baskets which contain the mass of heat absorbent material commonly comprised of stacked plate-like elements.
Conventional heat exchange baskets may be loaded axially into the rotor from the top end (duct end) or radially through the side of the rotor. Both designs require the positioning of the heavy, bulky heat exchange baskets. The conventional method for removing and replacing radially loaded heat exchange baskets is time consuming and requires the following:
1) The basket removal door is removed and stored.
2) A platform is retrieved from storage and mounted to a pair of columns positioned on either side of the basket removal door opening in the air preheater housing.
3) The heat exchange baskets are pulled from the air preheater onto the platform, lifted off of the platform, and removed from the area.
4) New baskets are placed on the platform and slid into the rotor.
5) The platform is removed and stored in a remote location.
6) The basket removal door is retrieved from storage and reinstalled.
Although the conventional basket installation/removal platform is functionally a good design, it is large and heavy, requiring a crane for installation and removal. Since the heat transfer matrix in the air preheater is long lasting (in many cases having a lifetime of over 5 years) the platform is not a commonly used maintenance item and generally must be stored away from the air preheater. The size and weight of the platform makes transporting the platform to and from storage a difficult task. In addition, the basket removal door must be completely removed and stored during the basket installation/removal process.
The present invention relates to a combined door and platform assembly for an air preheater having a housing with an access opening. The assembly includes a door frame which is fixedly mounted to the outer surface of the housing around the access opening. The bottom portion of a base is permanently, pivotally mounted to the door frame. The base is moveable from a vertical position, where the base acts as a door closing the access opening, to a horizontal position, where the base acts as a platform to facilitate removal and replacement of basketed materials disposed within the housing.
A pair of side safety panels are pivotally mounted to the sides of the base and an end safety panel is pivotally mounted to the free end of the base. Each of the safety panels is moveable between an extended position, where the safety panel extends substantially perpendicularly from the base, and a storage position, where the safety panel is disposed adjacent the base. The assembly includes stops preventing movement of the safety panels past the extended position and locks selectively holding the safety panels in the extended position. Each safety panel includes multiple posts, at least one hand rail mounted to the posts, and a kick board mounted to the bottom end portions of the posts. The kick board or the bottom end portions of the posts are pivotally mounted to the base.
Preferably, a pair of braces connect the side edges of the base to the side members of the door frame and thereby provide additional mechanical support to the base. Apparatus is provided to lock the base in the vertical position during operation of the air preheater.